Passive positioning utilizing beacon neighbor reports

ABSTRACT

Techniques for providing neighbor reports for use in passive positioning of a client station are disclosed. An example method for broadcasting network neighbor reports according to the disclosure includes generating a beacon transmission, determining a neighbor report count value, if the neighbor report count value is greater than zero, then broadcasting the beacon transmission including at least a beacon frame and the neighbor report count value, and decrementing the neighbor report count value; if the neighbor report count value is equal to zero, then broadcasting the beacon transmission including at least a beacon frame and a neighbor report, and resetting the neighbor count value.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/268,931, entitled “Passive Positioning Utilizing Beacon NeighborReports,” filed on May 2, 2014, which claims the benefit of U.S.Provisional Application No. 61/872,087, entitled, “Passive PositioningSchemes,” filed on Aug. 30, 2013, U.S. Provisional Application No.61/873,253, entitled, “Passive Positioning Schemes,” filed on Sep. 3,2013, U.S. Provisional Application No. 61/973,034, entitled, “PassivePositioning Utilizing Beacon Neighbor Reports,” filed Mar. 31, 2014, andU.S. Provisional Application No. 61/985,247, entitled, “PassivePositioning Utilizing Beacon Neighbor Reports,” filed Apr. 28, 2014,each of which is assigned to the assignee hereof and the contents ofwhich are incorporated herein by reference in their entirety.

BACKGROUND

Embodiments of the inventive subject matter generally relate to thefield of wireless communication and, more particularly, to providingneighbor reports in a passive positioning scheme for wirelesscommunication devices.

Various positioning techniques can be employed for determining theposition of a wireless communication device (e.g., a wireless local areanetwork (WLAN) device) based on receiving wireless communicationsignals. For example, positioning techniques can be implemented thatutilize time of arrival (TOA), the round trip time (RTT) of wirelesscommunication signals, received signal strength indicator (RSSI), or thetime difference of arrival (TDOA) of the wireless communication signalsto determine the position of a wireless communication device in awireless communication network. These factors may be used in conjunctionwith the known positions of one or more stations in the wireless networkto derive the location of the wireless communication device.

SUMMARY

An example of a wireless transceiver for providing network informationto a broadcast area according to the disclosure includes a memory and atleast one processor configured to periodically broadcast a beacontransmission with a neighbor report count value at a first interval, andperiodically broadcast a beacon transmission with a neighbor reportelement at a second interval.

Implementations of such a wireless transceiver may include one or moreof the following features. The neighbor report count value may be aninteger value, or may be another symbol to be used in a logicalcomparison operation (e.g., greater than, less than, equal to, etc . . .). An Access Point to Access Point (AP-to-AP) signaling parameter formatinformation element may be broadcast. The beacon transmission with theneighbor report count value and the beacon transmission with theneighbor report element may be in a Media Access Control (MAC) controlframe format. The beacon transmission with the neighbor report elementmay include a latitude value and a longitude value. The beacontransmission with the neighbor report element may include a civiclocation. The beacon transmission with the neighbor report element mayinclude a visitation index to indicate an order in which one or moreaccess points are to be visited.

An example of a method for broadcasting network neighbor reports with anaccess point according to the disclosure includes generating a beacontransmission, determining a neighbor report count value, if the neighborreport count value is greater than zero, then broadcasting the beacontransmission including at least a beacon frame and the neighbor reportcount value, and decrementing the neighbor report count value; if theneighbor report count value is equal to zero, then broadcasting thebeacon transmission including at least a beacon frame and a neighborreport, and resetting the neighbor count value.

Implementations of such a method may include one or more of thefollowing features. The neighbor report may include one or more neighborrecord elements. The neighbor record elements may include latitude andlongitude values. The beacon transmission may include at least a beaconframe, an AP-to-AP signaling parameter element, and a neighbor reportcount value. The AP-to-AP signaling parameter element may include aAP-to-AP Fine Timing Measurement (FTM) burst timeout value, and/orMinimum Delta Fine Timing Measurement (FTM) value. The neighbor countvalue may be a value between 200 and 1000. A beacon transmission may begenerated and broadcast at least every 100 milliseconds. The order thatthe neighbor report is transmitted is an indication of the order of theAPs that are going to be visited by the AP transmitting the neighborreport.

An example of a method for determining a current position with a clientstation according to the disclosure includes receiving a network beacontransmission with the client station, determining a neighbor reportcount value based on the beacon transmission, receiving a neighborreport if the neighbor report count value equals zero, determining alocation of one or more access points in the neighbor report, andcalculating a current position of the client station based at least inpart on the location of the one or more access points.

Implementations of such a method may include one or more of thefollowing features. FTM messages transmitted between two or more accesspoints in the wireless network may be received. An AP-to-AP signalingparameter element may be received by the client station if the neighborreport count equals zero.

Items and/or techniques described herein may provide one or more of thefollowing capabilities, as well as other capabilities not mentioned.Passive positioning of mobile network devices may be realized. Clientstation position request message traffic may be reduced. Access pointlocation information may be systematically delivered to multiple clientstations in a broadcast area. Network message traffic may be reduced.Further, it may be possible for an effect noted above to be achieved bymeans other than that noted, and a noted item/technique may notnecessarily yield the noted effect.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an example block diagram of a passive positioning scheme fordetermining the position of a client station.

FIG. 1B is an example network diagram of a wireless local area networkincluding a position server.

FIG. 2 is an example of a conceptual diagram of a fine timingmeasurement procedure.

FIGS. 3A and 3B are examples of AP-to-AP signaling schemes includingbeacon transmissions.

FIG. 4 is an exemplary AP-to-AP signaling parameter format informationelement.

FIG. 5 includes examples of beacon transmission frames.

FIG. 6A is flow diagram of a process for generating a beacontransmission including a neighbor report.

FIG. 6B is flow diagram of a process for periodically broadcastingbeacon transmissions.

FIG. 7 is flow diagram of a process for determining the position ofclient station.

FIG. 8A a block diagram of an electronic device for use in passivepositioning utilizing beacon neighbor reports.

FIG. 8B is a block diagram of an exemplary access point.

DETAILED DESCRIPTION

The description that follows includes exemplary systems, methods,techniques, instruction sequences, and computer program products thatembody techniques of the present inventive subject matter. However, itis understood that the described embodiments may be practiced withoutthese specific details. For instance, although examples refer to apassive positioning scheme for wireless local area network (WLAN)devices, embodiments are not so limited. In other embodiments, thepassive positioning scheme can be implemented by other wirelessstandards and devices (e.g., WiMAX devices). In other instances,well-known instruction instances, protocols, structures, and techniqueshave not been shown in detail in order not to obfuscate the description.

In wireless communication networks, determining the position of anelectronic device with wireless communication capabilities (e.g., withinan indoor or outdoor environment) can be a desired feature for users ofthe communication device (e.g., mobile phone users) and operators of thewireless communication network. In some systems, round-trip time (RTT)techniques can be implemented for determining the position of thecommunication device. For example, the communication device can transmita request message to multiple access points and can receive a responsemessage from each of the access points. The range between thecommunication device and each of the access points can be determined bymeasuring the round trip time between the request messages and thecorresponding response messages. The position of the communicationdevice can be determined by comparing the RTT information to the knownlocations of the access points. In some systems, time difference ofarrival (TDOA) techniques can be implemented for determining theposition of the communication device. For example, the communicationdevice can determine its position based on the difference between theranges from each of the access points to the communication device.However, the onus for initiating the RTT positioning operations (or theTDOA positioning operations) (e.g., transmitting the request message tothe access points) typically lies on the communication device. Becausethe communication device plays an active role in transmitting therequest messages to each access point, the communication device mayconsume a substantial amount of bandwidth and power. Moreover, if thewireless communication network comprises multiple such communicationdevices, such as in a crowded sports stadium or other popular venue,each communication device may be required to execute the RTT positioningoperations (or the TDOA positioning operations), increasing the trafficload in the wireless communication network.

A position calculation unit of the communication device can beconfigured to determine the position of the communication device basedon a passive positioning scheme to reduce the traffic load in thewireless communication network. The access points in the wirelesscommunication network can be configured to broadcast beacontransmissions and exchange fine timing messages periodically with one ormore neighboring access points (i.e., a target access point) in thewireless communication network. The access point can include a neighborreport in the beacon transmission. The neighbor report may include alist of access points, and the corresponding position information (e.g.,Latitude value, Longitude value, Altitude, Z axis information, Civiclocation information) for each access point. In an embodiment, theaccess point may determine RTT timing information associated with theone or more neighboring access points based on the time differencebetween a Fine Timing Measurement (FTM) message transmitted, and acorresponding acknowledgment (ACK) response message transmitted by thetarget access point. The position calculation unit can intercept the FTMmessage and the corresponding ACK message, and can determine TDOA timinginformation based on the time difference of arrival between the FTMmessage and the corresponding ACK message. The neighbor report mayinclude RTT measurement information comprising the RTT timinginformation associated with each access point in the neighbor report.The position calculation unit can then determine the position of thecommunication device based, at least in part, on the TDOA timinginformation, the RTT timing information, and position informationassociated with a predetermined number of network access points.

A passive positioning scheme utilizing beacon neighbor reports caneliminate transmissions initiated by the communication device to requestaccess point position information. This can minimize the impact of thecommunication device transmissions on the traffic load of the wirelesscommunication network. Furthermore, because the beacon neighbor reportscan be provided across the network (e.g., each access point canbroadcast a period neighbor report), the passive positioning scheme mayenable larger numbers of communication devices within the range of theaccess point network to compute their position without consuming thenetwork bandwidth associated with receiving and processing locationrequests from each of the communication devices.

Referring to FIG. 1A, an example block diagram of a passive positioningscheme utilizing beacon neighbor reports is shown. The passivepositioning scheme includes a wireless communication network 100comprising three access points 102, 104, 106, and a client station 120.The access points 102, 104, 106 may be an advanced WLAN access pointscapable of determining their own positions (e.g., a self-locating accesspoint). Each of the access points can select one or more other accesspoints in the wireless communication network 100 (e.g., within thecommunication range of one another). In some implementations, accesspoints can be arranged that one access point can be designated as amaster access point, and the other access points can be designated astarget access points. The client station 120 can be any suitableelectronic device (e.g., a notebook computer, a tablet computer, anetbook, a mobile phone, a gaming console, a personal digital assistant(PDA), inventory tag, etc.) with WLAN communication capabilities.Furthermore, in FIG. 1A, the client station 120 is within thecommunication range of one or more access points 102, 104, 106.

In an embodiment, the access point 102 transmits a periodic FTM messagesto one or more of the other access points 104, 106. The communicationbetween the access points 102, 104, 106 may follow a programmedschedule. For example, a first access point 102 may communicate with asecond access point 104 for a set amount of time (e.g., AP1-to-AP2period), and then the first access point 102 will switch to communicatewith a third access point 106 for a set amount of time (e.g., AP1-to-AP3period). During the communication period, the access point may send aseries of FTM messages and receive a corresponding number ofAcknowledgement messages (ACK). The FTM messages can comprise anidentifier associated with the first access point (e.g., a networkaddress of the access point 102), an identifier associated with a secondaccess point (e.g., a network address of the access point 104), asequence number that identifies each of the FTM messages, and atimestamp indicating the time instant at which each of the FTM messageswas transmitted and a timestamp indicating the time instant at whicheack Ack messages was received. Other information elements may beincluded in a FTM messages based on the network standards (e.g., IEEE802.11). In response to receiving the FTM message, the second accesspoint (e.g., the access point 104 in this example) can generate andtransmit a corresponding acknowledgment ACK response message. In oneimplementation, the ACK message indicates receipt of a FTM message.Other information elements may be included in an ACK message based onnetwork standards (e.g., IEEE 802.11).

In the example of FIG. 1A, the first access point 102 can exchangeFTM/ACK messages 108 with the second access point 104, and also canexchange FTM/ACK messages 110 with another access point 106. The secondaccess point 104 also can exchange FTM/ACK messages 112 with anotheraccess point 106. Each of the access points 102, 104, 106 may alsobroadcast beacon transmissions including a neighbor report.

The client station 120 can intercept the FTM messages and the ACKresponse messages to determine TDOA timing information associated withthe access points 102, 104, 106. The dashed lines 114, 116, 118represent the client station 120 intercepting the FTM/ACK messages 108,110, 112 exchanged between the access points 102, 104, 106 (e.g, the APcluster). The client station 120 can also receive beacon transmissionsfrom each of the access points 102, 104, 106.

In an embodiment, the access points 102, 104, 106 can broadcast periodicbeacon transmissions to the client station 120. The beacon transmissionmay include beacon frame information, such as defined in networkstandards document (e.g., 802.11, table 8-24). The beacon transmissionmay also include a neighbor report count value. The beacon transmissionmay periodically also include AP-to-AP signaling parameters and aneighbor report. The neighbor report may include position informationassociated with each neighboring access point, and may also include RTTand/or TDOA timing information for the neighboring access points. Theclient station 120 can receive the beacon transmission and can store theaccess point position information, the TDOA timing information, and theRTT timing information associated with the neighboring access points, ina predetermined memory location, a data structure, or another suitablestorage device.

The client station 120 is configured to determine a position based, atleast in part, on the AP position information included in the beacontransmissions. In some implementations, the client station 120 can usethe AP position information, in combination with the TDOA timinginformation, and/or the RTT timing information to construct a“positioning equation” in terms of the range between the client station120 and each of the predetermined number of access points. For example,on determining that AP position information, the TDOA timinginformation, and the RTT timing information associated with three targetaccess points are available, the client station 120 can solve threepositioning equations to determine a three-dimensional position of theclient station 120. It is noted that in other implementations, theclient station 120 can determine a position based on the AP positioninformation, the TDOA timing information, and the RTT timing informationassociated with any suitable number of access points. For example, aposition can be based on two independent positioning equations from theAP position information, the TDOA timing information, and the RTT timinginformation associated with two target access points to determine atwo-dimensional position of the client station 120.

Referring to FIG. 1B, an example network diagram of a wireless localarea network including a position server is shown. The network 150includes access points 102, 104, 106, a position server 152, and acommunication path 154. The position server 152 is a computing deviceincluding at least one processor and a memory and is configured toexecute computer executable instructions. For example, a position server152 comprises a computer system including a processor, non-transitorymemory, disk drives, a display, a keyboard, a mouse. The processor ispreferably an intelligent device, e.g., a personal computer centralprocessing unit (CPU) such as those made by Intel® Corporation or AMD®,a microcontroller, an application specific integrated circuit (ASIC),etc. The memory includes random access memory (RAM) and read-only memory(ROM). The disk drives include a hard-disk drive, a CD-ROM drive, and/ora zip drive, and may include other forms of drives. The display is aliquid-crystal display (LCD) (e.g., a thin-film transistor (TFT)display), although other forms of displays are acceptable, e.g., acathode-ray tube (CRT). The keyboard and mouse provide data inputmechanisms for a user. The position server 152 stores (e.g., in thememory) processor-readable, processor-executable software codecontaining instructions for controlling the processor to performfunctions described herein. The functions assist in the implementationof a passive positioning scheme utilizing beacon neighbor reports. Thesoftware can be loaded onto the memory by being downloaded via a networkconnection, uploaded from a disk, etc. Further, the software may not bedirectly executable, e.g., requiring compiling before execution. Theaccess points 102, 104, 106 are configured to communicate with theposition server 152 to exchange position information via thecommunication path 154. The communication path 154 can be a wide areanetwork (WAN) and can include the internet. The position server 152 caninclude a data structure (e.g., relational database, flat files) tostore AP neighbor information. For example, the position server 152 caninclude AP position information (e.g., lat./long., x/y), RTTinformation, SIFS information, and other information associated with anaccess point (e.g., SSID, MAC address, uncertainty value, coverage area,etc.). An access point 102, 104, 106 can communicate with the positionserver 152 and can retrieve, for example, AP neighbor information, SIFSinformation and RTT information for use in client station positioningsolutions. The configuration of the position server 152 is exemplaryonly, and not a limitation. In an embodiment, the position server 152may be connected directly to an access point, or the functionality maybe included in an access point. More than one position servers may beused. The position server 152 can include one or more databasescontaining position information associated with other access points onadditional networks. In an example, the position server 152 is comprisedof multiple server units.

Referring to FIG. 2, with further reference FIG. 1A, an example of aconceptual diagram of a fine timing measurement procedure 200 is shown.The general approach includes a first access point 202 (e.g., AP 1) anda second access point 204 (e.g., AP 2). The first and second accesspoints may be any of access points 102, 104, 106. As a generaldistinction, an access point may serve multiple stations but the termsas used herein are not so limited. The relevant operations describedherein may be performed on both stations and access points, thus theterms are used interchangeable. The fine timing measurement procedure200 may allow the first access point 202 to obtain its range with secondaccess point 204. An access point may perform this procedure withmultiple other access points in order to obtain its location. An FTMsession is an instance of a fine timing measurement procedure 200between the first access point 202 and the second access point 204, andmay include the associated scheduling and operational parameters of thatinstance. An FTM session is generally composed of a negotiation, ameasurement exchange and a termination. An access point may participatein multiple concurrent FTM sessions. Concurrent FTM sessions may occurwith responding stations that are members of different Basic ServiceSets (BSS) and possibly different Extended Service Sets (ESS), orpossibly outside of a BSS, each session using its own scheduling,channel and operational parameters. A responding access point may berequired to establish overlapping FTM sessions with a large number ofinitiating access points (e.g. a first access point 102 providingmeasurements to multiple other access points 104, 106 at stadium, a mallor a store). An access point may have multiple ongoing FTM sessions onthe same or different channels with different responding access points,while being associated to a particular access point for the exchange ofdata or signaling. To support the constraints of both the access points,during the negotiation the first access point 202 initially requests apreferred periodic time window allocation. The second access point 204subsequently responds by accepting or overriding the allocation requestbased on its resource availability and capability. Since some of thefirst access point's 202 activities may be non-deterministic and mayhave higher precedence than the FTM session (e.g. data transferinteraction with an associated AP), a conflict may prevent the firstaccess point 202 from being available at the beginning of a burstinstance determined by the second access point 204. In such an example,the first access point 202 may establish sessions with the second accesspoint 204, and a third access point (e.g., access point 106) ondifferent channels. Each of the sessions' burst periodicity may bedifferent and each of the stations' clock offsets may differ. Thus, overtime, some temporal conflicts may occur. To overcome this, during eachburst instance the initiating station may indicate its availability bytransmitting a trigger frame in the form of a Fine Timing MeasurementRequest frame. During each burst instance, the responding stationtransmits one or more fine timing measurement frames as negotiated.

In an example, the first access point may send a Fine Timing Measurementframe which may include a set of scheduling parameters to describe theinitiating station's availability for measurement exchange. The FineTiming Measurement frame may include a Fine Timing Measurement Parameterelement to define the parameters to be used during the fine timingmeasurement exchanges. For example, the stations can establish a MinimumDelta FTM time 208 to indicate the minimum time between consecutive FTMmessages. The timing of the burst instances are defined by a AP-to-APPartial Timer Synchronization Function (TSF) Timer value 210. TheAP-to-AP Partial TSF Timer value is a partial TSF timer at the beginningof the first burst instance and is the boundary of the burst period. TheAP-to-AP Burst Timeout value 216 is the time duration of each burstinstance starting at the boundary of a burst period. The AP-to-AP SwitchPeriod 214 is the interval from the beginning of one AP-to-AP burstinstance (e.g., 210) to the beginning of the following AP-to-AP burstinstance (e.g., 216). Exemplary values of the AP-to-AP switch periodgenerally range from 1 microsecond to a few seconds based on networkhardware and operational considerations. Within each burst instance,consecutive Fine Timing Measurement frames are generally spaced at leastthe Minimum Delta FTM time 208 apart. Within each burst instance theinitiating station may perform fine timing measurement on each FineTiming Measurement frame addressed to it.

Referring to FIGS. 3A, with further reference to FIGS. 1A and 2, anexample of a first AP-to-AP signaling scheme 300, including BeaconTransmissions, is shown. The first AP-to-AP signaling scheme 300includes a y-axis 302 with a list of the access points (e.g., AP1, AP2,AP3, AP4, AP5) in a cluster, an x-axis 304 to indicate the progressionof time, indications of time slots for beacon transmissions 306 for eachof the access points, indications of time slots for AP-to-AP FTMexchanges 308 for each of the access points, and time slots for BeaconTransmission with Neighbor Report 310. The first AP-to-AP signalingscheme 300 also includes indications of an AP-to-AP burst time out 312,an AP1 AP-to-AP Partial TSF Timer value 314, an AP2 AP-to-AP Partial TSFTimer value 316, an AP3 AP-to-AP Partial TSF Timer value 318, and anindication of an AP-to-AP Switch period 320. The AP-to-AP burst time out312 represents the time period of the FTM message exchanges representedin FIG. 2. Each of the AP-to-AP FTM exchange 308 elements represent theFTM message exchanges between the indicated access points (e.g.,AP1-to-AP2, AP1-to-A3, AP2-to-AP3, etc . . . ). Each of the partial TSFvalues 314, 316, 318 indicates the partial value of the respectiveresponding station's TSF timer at the time of the first burst instance.The AP-to-AP switch period 320 during which normal traffic exchangesoccur between the indicated stations (e.g., AP1-to-AP2, AP1-to-A3,AP2-to-AP3, etc . . . ). Each of the beacon transmissions 306 includes aneighbor report count value (e.g., 599, 598, 597 . . . 0). In operation,each access point (e.g., AP1, AP2, AP3, AP4, AP5) broadcasts a periodicbeacon transmission. The beacon transmissions 306 may conform toestablished Media Access Control (MAC) control frame formats, but willalso include a neighbor report count value. As depicted in FIG. 3A, thebeacon transmissions are provided at intervals of 100 ms, with theneighbor report count value decreasing in each subsequent transmission.Thus, in this example, 10 beacon transmissions are sent by each accesspoint every second and the neighbor report count value will cyclebetween 600 and zero every minute for each beacon transmission. Thebeacon intervals and neighbor report count values are exemplary only asother values may be used based on network requirements. When the networkreport count value reaches zero (e.g., on the 600^(th) beacontransmission), a beacon transmission with a neighbor report 310 isbroadcast. The neighbor report is described in more detail below, but ingeneral, a neighbor report provides client stations in the broadcastarea with information required to perform passive positioningcalculations. For example, a beacon transmission with a neighbor report310 may be used in the passive positioning methods described inco-pending Provisional U.S. Patent Application No. 61/873,253, filed onSep. 3, 2013, 2014, and titled “Passive Positioning Schemes.”

Referring to FIGS. 3B, with further reference to FIGS. 1A, 2 and 3A, anexample of a second AP-to-AP signaling scheme 350, including BeaconTransmissions, is shown. The second AP-to-AP signaling scheme 350includes a y-axis 302 with a list of the access points (e.g., AP1, AP2)in an exemplary cluster, an x-axis 304 to indicate the progression oftime, indications of time slots for beacon transmissions 306 for each ofthe access points, indications of time slots for AP-to-AP FTM exchanges308 for each of the access points, and time slots for BeaconTransmission with Neighbor Report 310. The list of two access points(e.g., AP1, AP2) is an example only, and not a limitation, as thecluster includes additional access points (e.g.., AP3, AP4, AP5, andAP6) which are not shown. The second AP-to-AP signaling scheme 350varies the order and the timing of the AP-to-AP FTM exchanges ascompared to the first AP-to-AP signaling scheme 300. The second AP-to-APsignaling scheme 350 also includes indications of an AP-to-AP burst timeout 352, an AP1 AP-to-AP Partial TSF Timer value 364, an AP2 AP-to-APPartial TSF Timer value 366, and an indication of an AP-to-AP switchperiod 370. The duration of the AP-to-AP switch period 370 may be around250 microseconds. The sequence and/or the relative time of the AP-to-APFTM exchanges 308 as compared to the beacon transmissions 306 and thebeacon transmissions with neighbor report 310 may vary based on networkconstraints.

Referring to FIG. 4, an AP-to-AP signaling parameter format informationelement 400 is shown. The AP-to-AP signaling parameter formatinformation element 400 may be part of a beacon transmission andbroadcast on a periodic basis. In an example, the AP-to-AP signalingparameter format information element 400 is included in the beacontransmission with a neighbor report 310. The AP-to-AP signalingparameter format information element 400 may be broadcast at an intervalthat is independent of the beacon transmissions. The AP-to-AP signalingparameter format information element 400 consists of a MAC frame formatmessage of 64 bits including an Element ID field (8 bits), a Lengthfield (8 bits), an N_AP Passive field (4 bits), an AP-to-AP Burst TimeOut field (8 bits), a Min. Delta FTM field, an AP-to-AP Partial TSFTimer field (16 bits), an AP-to-AP FTM Channel Spacing/Format field (6bits), and an AP-to-AP switch period field (8 bits). The ElementID andlength fields provide for message administration as known in the art.The N_AP Passive field contains an indication of the number of accesspoints to be visited during passive FTM exchanges. The AP-to-AP BurstTime Out indicates the duration of a burst instance. Typical values forthe burst instance are between 128 milliseconds and 250 microseconds. Anexample of the Min. Delta FTM field is depicted in FIG. 2 and representsthe minimum time between consecutive FTM messages. The AP-to-AP PartialTSF timer field indicates the partial value of a responding station TSFtimer at the time of the first AP-to-AP burst instance. The units may bethe same as the Partial TSF timer, which is 1 TU, 1024 microseconds. TheAP-to-AP FTM Channel Spacing/Format field indicates the desired packetbandwidth/format used by all the Fine Timing Measurement frames in a FTMsession. The AP-to-AP switch period field indicates the duration betweenswitch from one AP to the next (e.g., as depicted in FIGS. 3A and 3B).Other examples of the AP-to-AP signaling Parameter Format InformationElement 400 may include an FTM per Burst field (5 bits) to indicate theinterval between two consecutive burst instances.

Referring to FIG. 5, with further reference to FIGS. 3A, 3B and 4,examples of Beacon Transmissions frames are shown. A beacon transmissionwith a neighbor report frame 500 may include a beacon element 502, aneighbor report count element 504, and AP-to-AP Signaling Parameterelement 506, and a neighbor report element 508. The beacon element 502may include a beacon frame body such as described in the IEEE P802.11standard, table 8-24. The beacon frame body may be expanded to includethe neighbor report count element 504. The neighbor report count element504 provides information relating to the broadcast of the next neighborreport. As described in FIGS. 3A and 3B, in an example, the neighborreport count element can be a countdown value which decreases with eachsubsequent beacon transmission. The AP-to-AP Signaling Parameter element506 includes the fields described in FIG. 4 (i.e., the AP-to-APSignaling Parameter Format Information Element 400).

The neighbor report element 508 can be a MAC frame format such asdescribed in the IEEE P802.11 standard, FIG. 8-255. The neighbor reportelement 508 is included in the beacon transmission with a neighborreport frame 500 and thus is provided to the client stations on aperiodic basis. The neighbor report element 508 may include multipleneighbor record elements 510 (e.g., 510 a, 510 b, 510 c), with each ofthe multiple neighbor record elements containing information associatedwith a neighboring station. The neighbor report element may containposition information (e.g., latitude, longitude, altitude) for each ofthe neighbors. The neighbor report element may be constrained to onlyinclude a sufficient list of neighboring stations to perform passivepositioning and/or passive ranging. An exemplary neighbor record element510 may also include a Basic Service Set Identification (BSSID) field512, a BSSID Information field 514, an operating class field 516, achannel number field 518, a physical type field 520, and a visitationindex 522. Other sub-element fields may also be included. The BSSIDfield 512 represents the BSSID of the BSS being reported. The BSSIDInformation field 514 may be used to determine neighbor service settransition candidates. The operating class field 516 may be used toindicate operational frequency ranges (e.g., 2.4 GHz, 5 GHz), as well aschannel spacing. The channel number field 518 may be used to providechannel center frequency information. The physical type field 520indicates the PHY type of the AP indicted by the BSSID (e.g., ODFM, HT,DMG). The visitation index 522 indicates the priority (e.g., order) andhow each of the corresponding access points are visited. This index mayprevent additional signaling once the neighbor report element 508 isreceived. For example, AP1 may visit (e.g., send FTM packets) to AP2 atthe partial TSF timer time period. AP1 may then visit AP3 for a fixedamount of time, and then visit AP4. In general, if the visited AP is onthe same channel, the visiting AP will just send FTM packets. If thevisited AP is on a different channel, the visiting AP will go to the newchannel, send FTM packets to that AP, and then return to the originalchannel to serve the client stations. The order of the visits may bebased on the order of the visitation index in the network recordelements.

A beacon transmission with a neighbor count value 550 includes a beaconelement 502, and a neighbor report count element 504. The beacontransmission with a neighbor count value 550 is provided on a periodicbasis as described in FIGS. 3A and 3B, such that the value of theneighbor report count element 504 is reduced with each transmission. Theeffect is to provide the receiving station with a timer for anticipatingthe broadcast of the neighbor report. The decrementing counter is anexample only, and not a limitation, as other timer and/or countingprocesses may be used.

In operation, referring to FIG. 6A, with further reference to FIGS.1A-5, a process 600 for generating a beacon transmission including aneighbor report includes the stages shown. The process 600, however, isexemplary only and not limiting. The process 600 may be altered, e.g.,by having stages added, removed, or rearranged. For example, determiningand decrementing the neighbor report count value may occur at differentpoints in the process 600.

At stage 602, an access point is configured to generate a beacontransmission. The beacon transmission can be a MAC frame format with anadditional field to record a neighbor report count value. The beaconreport may include a beacon element 502 which is previously stored inmemory and a neighbor report count field can be updated when the beacontransmission is generated. In an example, a beacon transmission isgenerated every 100 milliseconds. The time may be modified based onnetwork parameters, such as the number access points in a network, thenumber of client stations, and the hardware capabilities of the accesspoints and client stations (e.g., 10, 50 100, 500, 1000 milliseconds).At stage 604, the access point is configured to determine a neighborreport count value. The neighbor report count value may be an integervalue and may represent the number of subsequent beacon transmissions tobe broadcast before neighbor information is provided to the clientstations in the broadcast area. The maximum neighbor report count valuecan be established based on the frequency of the beacon transmission, aswell as other network parameters. For example, when a beacontransmission is broadcast every 100 milliseconds, the maximum neighborreport count value can be 600 in order to provide neighbor reportinformation to the client stations once every minute.

At stage 606 the access point is configured to perform logic operationto determine whether the neighbor report count value is greater thanzero. If the neighbor report count value is greater than zero, then theprocess continues to stage 608 and the access point broadcasts thebeacon transmission including at least a beacon frame and the neighborreport count value. For example, the beacon transmission can be a beacontransmission with a neighbor count value 550 which is broadcast every100 ms. After the beacon transmission is broadcast, at stage 610, theaccess point is configured to decrement the neighbor report count valueby 1 such that when the process iterates back to stage 602, thesubsequent beacon transmission will have a neighbor report count valuethat is one less than the previously transmitted beacon transmission.

At stage 612, if the access point determines that the neighbor reportcount value is equal to zero, the access point is configured tobroadcast the beacon transmission including at least a beacon frame anda neighbor report. For example, the beacon transmission will be a beacontransmission with a neighbor report frame 500 as described in FIG. 5.The access point is then configured to reset the neighbor report countvalue to a predetermined value at stage 614. The neighbor report countvalue may be reset to any value (e.g., 1, 2, 20, 200, 400, 1000,10,000). A value of 600 was used for the example above. The neighborreport count value may be set to other values, and each access point ina network may have a different value. For example, a position server 152may evaluate the load on network resource and determine that a firstaccess point 102 should broadcast neighbor report information at a ratethat is twice that of a second access point 104. The timing of beacontransmissions, and the corresponding neighbor report information, may bemodified based on the operational requirements and capabilities of thenetwork 150.

In operation, referring to FIG. 6B, with further reference to FIGS.1A-5, a process 650 for periodically broadcasting beacon transmissionsincludes the stages shown. The process 650, however, is exemplary onlyand not limiting. The process 650 may be altered, e.g., by having stagesadded, removed, or rearranged.

At stage 652, a wireless transceiver (e.g., access point) is configuredto periodically broadcast a beacon transmission with a neighbor reportcount value at a first interval. The beacon transmission may be MACframe format with a data field indicating a neighbor report count value.The neighbor report count value may be an integer value, and the accesspoint may be configured to decrease the neighbor report count based onthe first interval. In an embodiment, the neighbor report count valuemay be any data to indicate approximately when a neighbor report elementwill be available to a client station. The duration of the firstinterval may be established based on network capabilities andperformance requirements. As previously discussed, an exemplary valuefor the first interval is approximately 100 milliseconds. Other valuesranging from microseconds to minutes may be used. In an example, thebeacon transmission with a neighbor report count value also includes anAP-to-AP signaling parameter format information element 400.

At stage 654, the wireless tranceiver is configured to periodicallybroadcast a beacon transmission with a neighbor report element at asecond interval. The duration of the second interval is larger than theduration of the first interval. In an example, the beacon transmissionwith a neighbor report element is broadcast in place of the beacontransmission with a neighbor report count value. The beacon transmissionwith a neighbor report element may include an AP-to-AP signalingparameter format information element 400. The beacon transmission may bea MAC frame format. The neighbor report element may include a pluralityof neighbor record elements. A visitation index in each of the neighborrecord elements may indicate the priority and how each of thecorresponding access points are visited. In the examples above, theduration of the second interval has been on the order of a minute. Thatis, every 600^(th) beacon transmission, when the beacon transmissionsare sent every 100 ms. The first and second intervals, however, are notso limited as other durations may be used based on network capabilitiesand performance expectations. For example, the neighbor report elementin a small network may be broadcast more often because a neighbor reportconsisting of a few neighbor record elements may place little demand onthe available bandwidth. Other performance issues such as latency andexpected mobility of the client stations may also be used to determinethe duration of the first and second intervals.

In operation, referring to FIG. 7, with further reference to FIGS. 1A-5,a process 700 for determining the position of a client station includesthe stages shown. The process 700, however, is exemplary only and notlimiting. The process 700 may be altered, e.g., by having stages added,removed, or rearranged. For example, a position calculation can be madeby the processors on the client station 120 (i.e., local), or by theprocessors in the position server 152 (i.e., remote). Displaying thecurrent position of a client station at stage 714 is optional.

At stage 702, a client station 120 is configured to receive a beacontransmission from an access point. The beacon transmission may include abeacon frame element and a neighbor report count element. The beaconframe element may include fields related to general network information.At stage 704, the client station 120 is configured to evaluate thereceived beacon transmission and determine a value of the neighborreport count element. The neighbor report count value may be an integer,or other value that may be used in a logical comparison operation. Forexample, as stage 706, a logical comparison is performed by the clientstation 120 to determine if the neighbor report count value is greaterthan zero. If the neighbor report count value is greater than zero, thenthe client station 120 continues to monitor the network and may receiveanother beacon transmission at stage 702 when the process iterates.

At stage 708, if the result of the logical operation at stage 706 fails,the client station is configured to receive a neighbor report. Theneighbor report may be included in the beacon transmission. For example,the beacon transmission received at stage 702 may be a beacontransmission with a neighbor report frame 500 previously discussed.Receiving the neighbor report may include receiving the beacontransmission, parsing the received frames, and storing the respectivefields in the frames. At stage 710, the client station 120 is configuredto determine the location of one or more access points in the neighborreport. In an example, a neighbor report includes one or more neighborrecord elements 510, and each record element includes locationinformation associated with an access point. The record elements mayalso include RTT and RSSI information for the neighbors. The neighborrecord elements may be indexed based on the importance of the neighborin a position calculation. For example, the neighbors may be indexedbased on geometric orientation (i.e., triangulation) in an effort toimprove the position calculation.

At stage 712, the client station 120, or the position server 152, may beconfigured to determine the current position of the client station basedat least in part on the location of the one or more access points. Aspreviously described, in a passive positioning scheme, the clientstation 120 is configured to receive and capture information related tothe FTM messages flowing between the access points (e.g., 108, 110,112). The client station 120 includes a positioning unit configured toutilize the information included in the neighbor report in conjunctionwith FTM message information (e.g., RTT, RSSI, TOA, and TDOA data) todetermine the current position of the client station. The currentposition of the client station may be stored locally, or on the positionserver 152, or on other network resources, and may be used with locationbased services. Optionally, the client station 120 may be configured todisplay current position of the client station at stage 714.

Embodiments may take the form of an entirely hardware embodiment, anentirely software embodiment (including firmware, resident software,micro-code, etc.) or an embodiment combining software and hardwareaspects that may all generally be referred to herein as a “circuit,”“module” or “system.” Furthermore, embodiments of the inventive subjectmatter may take the form of a computer program product embodied in anytangible medium of expression having computer usable program codeembodied in the medium. The described embodiments may be provided as acomputer program product, or software, that may include amachine-readable medium having stored thereon instructions, which may beused to program a computer system (or other electronic device(s)) toexecute (e.g., perform) a process according to embodiments, whetherpresently described or not, since every conceivable variation is notenumerated herein. A machine-readable medium includes any mechanism forstoring or transmitting information in a form (e.g., software,processing application) readable by a machine (e.g., a computer). Amachine-readable medium may be a non-transitory processor-readablestorage medium, a machine-readable storage medium, or a machine-readablesignal medium. A machine-readable storage medium may include, forexample, but is not limited to, magnetic storage medium (e.g., floppydiskette); optical storage medium (e.g., CD-ROM); magneto-opticalstorage medium; read only memory (ROM); random access memory (RAM);erasable programmable memory (e.g., EPROM and EEPROM); flash memory; orother types of tangible medium suitable for storing electronicinstructions. A machine-readable signal medium may include a propagateddata signal with computer readable program code embodied therein, forexample, an electrical, optical, acoustical, or other form of propagatedsignal (e.g., carrier waves, infrared signals, digital signals, etc.).Program code embodied on a machine-readable signal medium may betransmitted using any suitable medium, including, but not limited to,wireline, wireless, optical fiber cable, RF, or other communicationsmedium.

Computer program code for carrying out operations of the embodiments maybe written in any combination of one or more programming languages,including an object oriented programming language such as Java,Smalltalk, C++ or the like and conventional procedural programminglanguages, such as the “C” programming language or similar programminglanguages. The program code may execute entirely on a user's computer,partly on the user's computer, as a stand-alone software package, partlyon the user's computer and partly on a remote computer or entirely onthe remote computer or server. In the latter scenario, the remotecomputer may be connected to the user's computer through any type ofnetwork, including a local area network (LAN), a personal area network(PAN), or a wide area network (WAN), or the connection may be made to anexternal computer (for example, through the Internet using an InternetService Provider).

Referring to FIG. 8A is a block diagram of one embodiment of anelectronic device 800 for use in passive positioning utilizing beaconneighbor reports. In some implementations, the electronic device 800 maybe a client station 120 embodied in a device such as a notebookcomputer, a tablet computer, a netbook, a mobile phone, a smart phone, agaming console, a personal digital assistant (PDA), or an inventory tag.The electronic device 800 may be other electronic systems such as a HomeNode B (HNB) device with a wireless transceiver and positioningcapabilities (e.g., a type of access point). The electronic device 800includes a processor unit 802 (possibly including multiple processors,multiple cores, multiple nodes, and/or implementing multi-threading,etc.). The electronic device 800 includes a memory unit 806. The memoryunit 806 may be system memory (e.g., one or more of cache, SRAM, DRAM,zero capacitor RAM, Twin Transistor RAM, eDRAM, EDO RAM, DDR RAM,EEPROM, NRAM, RRAM, SONOS, PRAM, etc.) or any one or more of the abovealready described possible realizations of machine-readable media. Theelectronic device 800 also includes a bus 810 (e.g., PCI, ISA,PCI-Express, HyperTransport®, InfiniBand®, NuBus, AHB, AXI, etc.), andnetwork interfaces 804 that include at least one of a wireless networkinterface (e.g., a WLAN interface, a Bluetooth® interface, a WiMAXinterface, a ZigBee® interface, a Wireless USB interface, etc.) and awired network interface (e.g., an Ethernet interface, etc.).

The electronic device 800 also includes a communication unit 808. Thecommunication unit 808 comprises a positioning unit 812, a receiver 814,a transmitter 816, and one or more antennas 818. The transmitter 816,the antennas 818, and the receiver 814 form a wireless communicationmodule (with the transmitter 816 and the receiver 814 being atransceiver 820). The transmitter 816 and the receiver 814 areconfigured to communicate bi-directionally with one or more clientstations and other access points via a corresponding antennas 818. Insome embodiments, the electronic device 800 can be configured as a WLANstation with positioning determining capabilities (e.g., a type ofaccess point). The positioning unit 812 can detect the FTMrequest/response messages exchanged between the access points todetermine TDOA timing information associated with the access points. Thepositioning unit 812 can determine the position of the electronic device800 based, at least in part, on the TDOA timing information, and the APposition information, as described above with reference to FIGS. 1A-7.In some embodiments, the access points 102, 104, 106 can also beconfigured as the electronic device 800 of FIG. 8A. In this embodiment,the access points can use their processing capabilities to execute theirrespective operations described above. Any one of these functionalitiesmay be partially (or entirely) implemented in hardware and/or on theprocessor unit 802. For example, the functionality may be implementedwith an application specific integrated circuit, in logic implemented inthe processor unit 802, in a co-processor on a peripheral device orcard, etc. Further, realizations may include fewer or additionalcomponents not illustrated in FIG. 8A (e.g., video cards, audio cards,additional network interfaces, peripheral devices, etc.). The processorunit 802, the memory unit 806, and the network interfaces 804 arecoupled to the bus 810. Although illustrated as being coupled to the bus810, the memory unit 806 may be coupled to the processor unit 802.

Referring to FIG. 8B, an example of an Access Point (AP) 850 comprises acomputer system including a processor 851, memory 852 including software854, a transmitter 856, antennas 858, and a receiver 860. In someembodiments, the access points 102, 104, 106 can also be configured asthe AP 850 of FIG. 8B. The transmitter 856, antennas 858, and thereceiver 860 form a wireless communication module (with the transmitter856 and the receiver 860 being a transceiver). The transmitter 856 isconnected to one of the antennas 858 and the receiver 860 is connectedto another of the antennas 858. Other example APs may have differentconfigurations, e.g., with only one antenna 858, and/or with multipletransmitters 856 and/or multiple receivers 860. The transmitter 856 andthe receiver 860 are configured such that the AP 850 can communicatebi-directionally with the client station 120 via the antennas 858. Theprocessor 851 is preferably an intelligent hardware device, e.g., acentral processing unit (CPU) such as those made by ARM®, Intel®Corporation, or AMD®, a microcontroller, an application specificintegrated circuit (ASIC), etc. The processor 851 could comprisemultiple separate physical entities that can be distributed in the AP850. The memory 852 includes random access memory (RAM) and read-onlymemory (ROM). The memory 852 is a processor-readable storage medium thatstores the software 854 which is processor-readable,processor-executable software code containing processor-readableinstructions that are configured to, when executed, cause the processor851 to perform various functions described herein (although thedescription may refer only to the processor 851 performing thefunctions). Alternatively, the software 854 may not be directlyexecutable by the processor 851 but configured to cause the processor851, e.g., when compiled and executed, to perform the functions.

While the embodiments are described with reference to variousimplementations and exploitations, it will be understood that theseembodiments are illustrative and that the scope of the inventive subjectmatter is not limited to them. In general, techniques for a passivepositioning utilizing beacon neighbor reports for wireless communicationdevices as described herein may be implemented with facilitiesconsistent with any hardware system or hardware systems. Manyvariations, modifications, additions, and improvements are possible.

Plural instances may be provided for components, operations, orstructures described herein as a single instance. Finally, boundariesbetween various components, operations, and data stores are somewhatarbitrary, and particular operations are illustrated in the context ofspecific illustrative configurations. Other allocations of functionalityare envisioned and may fall within the scope of the inventive subjectmatter. In general, structures and functionality presented as separatecomponents in the exemplary configurations may be implemented as acombined structure or component. Similarly, structures and functionalitypresented as a single component may be implemented as separatecomponents. These and other variations, modifications, additions, andimprovements may fall within the scope of the inventive subject matter.

As used herein, including in the claims, unless otherwise stated, astatement that a function or operation is “based on” an item orcondition means that the function or operation is based on the stateditem or condition and may be based on one or more items and/orconditions in addition to the stated item or condition.

Further, more than one invention may be disclosed.

1. An access point for providing network information to a broadcastarea, comprising: a memory; a wireless transceiver; and at least oneprocessor, wherein the wireless transceiver is configured to: broadcasta beacon transmission with a neighbor report count value at a firstinterval of time, wherein the neighbor report count value indicates anumber of subsequent beacon transmissions to be broadcast before aneighbor report is provided; and broadcast the beacon transmission withthe neighbor report and an Access Point to Access Point (AP-to-AP)signaling parameter format information element at a second interval oftime, wherein the second interval of time is greater than the firstinterval of time and the AP-to-AP signaling parameter format informationelement includes a AP-to-AP switch period to indicate a duration of timeduring which the wireless transceiver will transmit one or more FineTiming Measurement (FTM) packets to a second access point.
 2. The accesspoint of claim 1 wherein the AP-to-AP switch period is greater than thefirst interval of time.
 3. The access point of claim 1 wherein theAP-to-AP switch period is less than the first interval of time.
 4. Theaccess point of claim 1 wherein the neighbor report includes a BasicService Set Identification (BSSID) value associated with the secondaccess point.
 5. The access point of claim 1 wherein the neighbor reportincludes a plurality of BSSID values associated with a plurality ofaccess points and the AP-to-AP switch period indicates the duration oftime during which the wireless transceiver will transmit one or more FTMpackets to each access point in the plurality of access points.
 6. Theaccess point of claim 5 wherein the neighbor report includes avisitation index for each of the plurality of access points to indicatean order in which the wireless transceiver will send FTM packets to therespective access points.
 7. The access point of claim 5 wherein theneighbor report includes a channel number for each of the plurality ofaccess points to indicate a channel on which the wireless transceiverwill send FTM packets to the respective access point.
 8. A method ofproviding network information to a broadcast area with a wirelesstransceiver, comprising: broadcasting a periodic beacon transmissionwith a neighbor report count value at a first interval of time, whereinthe neighbor report count value indicates a number of subsequent beacontransmissions to be broadcast before a neighbor report is provided; andbroadcasting the periodic beacon transmission with the neighbor reportand an Access Point to Access Point (AP-to-AP) signaling parameterformat information element at a second interval of time, wherein thesecond interval of time is greater than the first interval of time andthe AP-to-AP signaling parameter format information element includes aAP-to-AP switch period to indicate a duration of time during which thewireless transceiver will transmit one or more Fine Timing Measurement(FTM) packets to an access point.
 9. The method of claim 8 wherein theAP-to-AP switch period is greater than the first interval of time. 10.The method of claim 8 wherein the AP-to-AP switch period is less thanthe first interval of time.
 11. The method of claim 8 wherein theneighbor report includes a Basic Service Set Identification (BSSID)value associated with the access point.
 12. The method of claim 8wherein the neighbor report includes a plurality of BSSID valuesassociated with a plurality of access points and the AP-to-AP switchperiod indicates the duration of time during which the wirelesstransceiver will transmit one or more FTM packets to each access pointin the plurality of access points.
 13. The method of claim 12 whereinthe neighbor report includes a visitation index for each of theplurality of access points to indicate an order in which the wirelesstransceiver will send FTM packets to the respective access points. 14.The method of claim 12 wherein the neighbor report includes a channelnumber for each of the plurality of access points to indicate a channelon which the wireless transceiver will send FTM packets to therespective access point.
 15. An apparatus for providing networkinformation to a broadcast area with an access point, comprising: meansfor broadcasting a periodic beacon transmission with a neighbor reportcount value at a first interval of time, wherein the neighbor reportcount value indicates a number of subsequent beacon transmissions to bebroadcast before a neighbor report is provided; and means forbroadcasting the periodic beacon transmission with the neighbor reportand an Access Point to Access Point (AP-to-AP) signaling parameterformat information element at a second interval of time, wherein thesecond interval of time is greater than the first interval of time andthe AP-to-AP signaling parameter format information element includes aAP-to-AP switch period to indicate a duration of time during which theaccess point will transmit one or more Fine Timing Measurement (FTM)packets to a second access point.
 16. The apparatus of claim 15 whereinthe AP-to-AP switch period is greater than the first interval of time.17. The apparatus of claim 15 wherein the AP-to-AP switch period is lessthan the first interval of time.
 18. The apparatus of claim 15 whereinthe neighbor report includes a Basic Service Set Identification (BSSID)value associated with the second access point.
 19. The apparatus ofclaim 15 wherein the neighbor report includes a plurality of BSSIDvalues associated with a plurality of access points and the AP-to-APswitch period indicates the duration of time during which the means forbroadcasting will transmit one or more FTM packets to each access pointin the plurality of access points.
 20. The apparatus of claim 19 whereinthe neighbor report includes a visitation index for each of theplurality of access points to indicate an order in which the means forbroadcasting will send FTM packets to the respective access points. 21.The apparatus of claim 19 wherein the neighbor report includes a channelnumber for each of the plurality of access points to indicate a channelon which the means for broadcasting will send FTM packets to therespective access point.
 22. A non-transitory processor-readable storagemedium comprising processor-readable instructions configured to causeone or more processors to provide network information to a broadcastarea with a first access point, comprising: code for broadcasting aperiodic beacon transmission with a neighbor report count value at afirst interval of time, wherein the neighbor report count valueindicates a number of subsequent beacon transmissions to be broadcastbefore a neighbor report is provided; and code for broadcasting theperiodic beacon transmission with the neighbor report and an AccessPoint to Access Point (AP-to-AP) signaling parameter format informationelement at a second interval of time, wherein the second interval oftime is greater than the first interval of time and the AP-to-APsignaling parameter format information element includes a AP-to-APswitch period to indicate a duration of time during which the accesspoint will transmit one or more Fine Timing Measurement (FTM) packets toa second access point.
 23. The storage medium of claim 22 wherein theAP-to-AP switch period is greater than the first interval of time. 24.The storage medium of claim 22 wherein the AP-to-AP switch period isless than the first interval of time.
 25. The storage medium of claim 22wherein the neighbor report includes a Basic Service Set Identification(BSSID) value associated with the second access point.
 26. The storagemedium of claim 22 wherein the neighbor report includes a plurality ofBSSID values associated with a plurality of access points and theAP-to-AP switch period indicates the duration of time during which thefirst access point will transmit one or more FTM packets to each accesspoint in the plurality of access points.
 27. The storage medium of claim26 wherein the neighbor report includes a visitation index for each ofthe plurality of access points to indicate an order in which the firstaccess point will send FTM packets to the respective access points. 28.The storage medium of claim 26 wherein the neighbor report includes achannel number for each of the plurality of access points to indicate achannel on which the first access point will send FTM packets to therespective access point.